A Delta Airlines Airbus A350 aircraft waits to take off at Beijing Capital International Airport on July 25, 2018. File Photos: VCG

Delta Air Lines Tuesday announced it would become the second US airline to resume direct flights to Shanghai beginning December 3.

United Airlines resumed direct flights between San Francisco and Shanghai on October 21 and would no long stop in Seoul, South Korea. 

Delta will offer two weekly direct flights from Seattle and Detroit to Shanghai, according to Wong Hong, Delta's China President.

The two carriers had suspended flights between the US and China since February due to the coronavirus pandemic, and both resumed flights from the US to China in June and July with a stop in Seoul.

The resumption of direct flights between China and the US is in accordance with approved flight quotas, and there has been no loosening of China's strict policy on overseas flights, Lin Zhijie, a market watcher told the Global Times on Tuesday. 

As COVID-19 cases rebound sharply in countries from North America to Europe, Chinese embassies in several countries, including Russia, the US and the UK, are now requiring all passengers flying to China to present a negative result blood test called a serum IgM antibody test, in addition to the previously required negative test result for a nucleic acid test, before they are to be allowed to board a flight to China.

Civil Aviation Administration of China has repeatedly emphasized epidemic prevention during autumn and the coming winter, and preventing imported cases is a top priority. 

Experts said that the resumption of direct flights between China and the US is a good sign for travelers, but it doesn't mean a full recovery of international flights to China.

A number of other aviation markets are now beginning to offer international flights, in a sign of an initial recovery in the aviation sector. 

In October, South Africa reopened its borders, and Lufthansa, Emirates, and KLM have resumed routes to major airports in South Africa. British Airways resumed flights from the UK to Belgium, Ireland, Germany, Italy and many other European countries.

With the arrival of autumn and the coming winter in the northern hemisphere, new epidemics have emerged in many countries around the world, which has caused a new blow to the international air transport market that has had shown signs of recovery. 

Earlier this month, the International Air Transport Association (IATA) lowered its passenger forecast, saying passenger traffic in 2020 will drop 66 percent year-on-year. The association's previous estimate predicted a drop of 63 percent. 

IATA predicts airlines around the world won't see positive revenue growth until 2022, and many governments have already or will soon end financial assistance to their aviation industry, leaving airlines to face continued challenges.